1. Field of the Invention
The present invention relates to downsizing of an optical transmitter-receiver module.
2. Description of the Related Art
In recent years, application domains of optical communications rapidly shift from a trunk transmission system to a subscriber loop system. For this reason, the downsizing and cost reduction of an optical transmitter-receiver module used for an optical subscriber loop system is important. Responding to this object, an application of the optical transmitter-receiver module, which uses a waveguide to integrate a transmission function and a reception function, is entering into a mainstream. In this context, the optical transmitter-receiver module, onto which an optical transmitter-received subassembly is provided, has been developed. For example, Japanese Patent Application Laid-open No. Hei 11-68705 discloses a wavelength division multiplexing (WDM) optical transmitter-receiver module. Japanese Patent Application Laid-open No. 2007-28539 also discloses an optical transmitter-receiver module which more simply duplexes a single-core two-way optical transmission system.
FIG. 5 shows an example of an optical transmitter-receiver subassembly 90 onto which leads are provided. The optical transmitter-receiver subassembly 90 includes a planar lightwave circuit (planar lightwave optical circuit) 92 and a transimpedance amplifier integrated circuit (IC) 22 provided onto a ceramic package 91. A flange 96 fixes an optical fiber 95 Leads (terminals) 93 are provided onto the ceramic package 91 to input/output a current between the planar lightwave circuit 92 and the exterior. The leads 93 are soldered onto a printed circuit board (printed-wiring board) to electrically connect the optical transmitter-receiver subassembly 90 to the printed circuit board. For illustrative purposes, FIG. 5 visibly shows the state where the planar lightwave circuit 92 and the like are provided.
However, the optical transmitter-receiver subassembly is manually mounted onto the printed circuit board through the leads. Therefore, the printed circuit board requires an area for soldering the leads onto it. Moreover, a Multi Source Agreement (MSA) defines the size of the optical transmitter-receiver module. The MSA allows a product package size, pin arrangements, and specifications to be shared by a plurality of vendors to establish a stable product supply system. Therefore, the size of the single optical transmitter-receiver module limits the number of optical transmitter-receiver modules incorporated into a communication device. As a result, it is difficult to increase the number of channels.
Moreover, with the increase in the use of the optical subscriber loop systems, an optical communication device is desired to be reduced in size. Therefore, it is necessary to reduce the size of the optical transmitter-receiver module and to provide the optical transmitter-receiver module at a higher density.